This invention generally relates to wireless code division multiple access communication systems. In particular, the invention relates to modeling such systems.
FIG. 1 is an illustration of a simplified wireless code division multiple access (CDMA) communication system. The system has a plurality of base stations 201–204 (20) communicating with a plurality of user equipments (UEs) 221–228 (22). Each UE 22 typically communicates with the base station 20 with the strongest signal. However, based on the allocation of radio resources, UEs 22 may communicate with base stations 20 not having the strongest signal. To illustrate, since base station 202 has a heavier loading (UEs 223–226) than base station 203, UE 224 may communicate with base station 203 instead of closer base station 202.
In such systems, radio resources need to be allocated to the users (UEs 22). This is commonly referred to as radio resource management. In a frequency division duplex (FDD)/CDMA communication system, the system allocates to users codes within frequency spectrums for communication (to support a session). In hybrid time division multiple access (TDMA)/CDMA communication systems, users are not only allocated codes within frequency spectrums but also selected time slots out of a set of time slots within the frequency spectrums for communication. In time division duplex (TDD)/CDMA communication systems, uplink and downlink communications are allocated to different time slots within a given frequency spectrum.
Due to the numerous combinations of potential allocations of resources to users, it is difficult to make an optimum allocation. As a system is operating, it is extremely difficult to take into account all the variables required to make resource allocations. Accordingly, it is desirable to be able to model such systems for use in evaluating resource allocation approaches.